This invention relates to conductor metallizations, and more particularly, to glass frits useful in producing metallizations to produce high-adhesion conductors on dielectric substrates.
Metallizations fired onto a dielectric substrate to produce conductor patterns usually comprise noble metals and an inorganic binder and are applied to the substrate as a dispersion thereof in an inert liquid medium. The metallic component provides the functional utility while the binder (e.g., glass, Bi.sub.2 O.sub.3, etc.) bonds the metal to the substrate.
Silver (including Pd/Ag) conductor metallizations (glass frit plus noble metal) presently employed in high-performance electronic applications for producing fired conductor patterns on dielectric substrates are often deficient in that properties such as ease of solderability and high adhesion (initial and thermally aged) are not obtained simultaneously. To prevent adhesive failure, leads to conductor patterns are often designed to impart a mechanical strength which compliments the soldered bond strength. This is done by swaging pins in the ceramic substrate prior to soldering or by using clip-on leads. Better adhesion of the conductor to the substrate would eliminate these steps and present cost savings. Furthermore, in certain applications, not only is a conductor fire and a resistor fire necessary with a given substrate, but also an encapsulation fire (glass) at about 500.degree.C., which thermal treatment often leads to poor solderability in Pd/Ag conductors located elsewhere on the substrate.